This application is a 371 of PCT/EP99/01474, filed Mar. 8, 1999.
The present invention relates to a novel, inventive process for the preparation of biphenyls or aromatic olefins by coupling reactions using allyl palladium catalysts and novel allyl palladium catalysts.
Biphenyls and aromatic olefins can have versatile uses as chemical specialities for the preparation of liquid crystals, as photoinitiators, UV absorbers, fluorescent whitening agents, ligands for catalysts and as starting materials for the preparation of intermediates for agro-chemicals and pharmaceutical products.
A frequently used method for the synthesis of biphenyls is the palladium-catalysed cross-coupling (so-called Suzuki coupling) in which iodine aromatic compounds or bromine aromatic compounds or arylsulfonates are reacted with arylboron derivatives in the presence of palladium catalysts. This method is described, inter alia, in N. Miyaura et al., Synthetic Communications, 11 (1981), 513; A. Suzuki in Metal-catalyzed Cross-coupling Reactions, chapter 2, Wileyxe2x80x94VCH, Weinheim 1998, in U.S. Pat. No. 5,130,439 and in EP-A-470 795.
A frequently used method for the synthesis of aromatic olefins is the palladium-catalysed coupling reaction, the socalled Heck reaction, in which iodine aromatic compounds or bromine aromatic compounds are reacted with olefins in the presence of palladium catalysts. This method is described, inter alia, in R. F. Heck, acc. Chem. Res. 1979, 12, 146; R. F. Heck, Org. React. 1982, 27, 345; and in R. F. Heck, Palladium Reactions in Synthesis, Academic Press, London 1985, S. Brxc3xa4se and A. De Meijere in Metal-catalyzed Cross-coupling Reactions, chapter 3, Wileyxe2x80x94VCH, DE-Weinheim 1998.
In spite of their interesting broad utility, these methods have drawbacks regarding the synthesis. For example, if one does not want to use the catalyst in amounts of more than 1 mol %, then only small amounts of product can be produced on a laboratory scale by the cited coupling reactions. In the Suzuki reaction, the use of conventional palladium catalysts, e.g. Pd(PPh3)4, Pd(OAc)2 and triphenyl phosphine, results in undesirable side reactions through aryl transference from the catalyst to the substrate; D. F. O""Keefe et al. Tetrahedron Left., 1992, 6679. The recovery of the palladium catalyst is elaborate in the case of the cited coupling reactions, the separation of the palladium residue from the reaction mixture requiring first the conversion of that residue into a palladium salt, e.g. palladium chloride or palladium acetate.
It is the object of this invention to find suitable catalysts for coupling reactions of biphenyls of the Suzuki cross-coupling type and of aromatic olefins of the Heck coupling type which promise improved turnover numbers (mol product/mol catalyst) and enhanced reactivity and selectivity over the catalysts used in such coupling reactions.
This object is achieved by the present invention which provides a novel, inventive process for the preparation of biphenyls and aromatic olefins using olefinic palladium complex compounds.
This invention relates to a process for the preparation of biphenyls of formula 
wherein A and B define substituents; m and n define integers from 0 to 5 and the number of substituents at the phenyl radicals D and E; or
of aromatic olefins of formula 
xe2x80x83wherein C defines substituents, o defines integers from 0 to 5 as well as the number of substituents at the phenyl radical F, and R6, R7 and R8 are hydrogen or substituents, which process comprises
a) subjecting a phenyl derivative of formula 
xe2x80x83wherein A, B, m and n have the meanings cited for formula I and X is a leaving group, for the preparation of the biphenyls (I) to a coupling reaction with an arylboronic acid derivative of formula 
xe2x80x83wherein A, B, m and n have the meanings cited for formula I and Y is thexe2x80x94B(OH)2 group or mono- or diester derivatives ofxe2x80x94B(OH)2; and
b) subjecting a phenyl derivative of formula 
xe2x80x83wherein C and o have the meanings cited for formula II and X is a leaving group, for the preparation of the aromatic olefins (II) to a coupling reaction with an olefin of formula 
xe2x80x83wherein R6, R7 and R8 have the meanings cited for formula 11, each in the presence of a catalytically effective amount of an olefinic palladium complex compound of formula 
xe2x80x83wherein L is a neutral ligand having electron-donor properties, Z is an anionic ligand and D is a substituent, and p is an integer from 0 to 5 and defines the number of substituents at the allyl group; or
axe2x80x2) subjecting a phenyl derivative (III a) or (IIIb), wherein A, B, m and n have the meanings cited for formula I and X is chloro, bromo or iodo, for the preparation of the biphenyls (I) to a coupling reaction with an arylboronic acid derivative (IV a) or (IV b), wherein A, B, m and n have the meanings cited for formula I and Y is thexe2x80x94B(OH)2 group or mono- or diester derivatives ofxe2x80x94B(OH)2; or
bxe2x80x2) subjecting a phenyl derivative (V), wherein C and o have the meanings cited for formula II and X is bromo or iodo, for the preparation of the aromatic olefins (II) to a coupling reaction with an olefin (VI), wherein R6, R7 and R8 have the meanings cited for formula II, in the presence of a catalytically effective amount of an olefinic, ionic palladium complex compound of formula 
xe2x80x83wherein Z1 and Z2 are anionic ligands and K+ is a non-coordinating cation and D and p have the cited meanings, and isolating the biphenyl (I) or the condensed aromatic olefin (II) after the completion of the process variants a), b), axe2x80x2) or bxe2x80x2).
The catalysts used in this process can be easily obtained by simple synthesis, for example by the method of B.{dot over (A)}kermark et al., Organometallics 1987, 6, 620-628, and have substantially improved reactivity and selectivity. After the reaction is complete, the dissolved olefinic palladium complex compounds can be degraded to palladium black using atmospheric oxygen. Using the method of Y. Inoue et al. Synthesis 1984, 3, 244, this residue can be used again directly for the catalyst synthesis without any detour over the conversion into a palladium salt, such as palladium chloride or palladium acetate.
The terms and denotations used in this description of the invention preferably have the following meanings:
Biphenyls (I) are preferably substituted at the phenyl ring D by 1 to 5 substituents from the group A containing the substituents R1, R2, R3, R4 and R5, and at the phenyl ring E also preferably by 1 to 5 substituents from the group B containing the substituents from the group R6, R7, R8, R9 and R10. Suitable substituents are listed in the List of Radical Names, which is valid according to IUPAC Rules, and remain unchanged under the conditions of the coupling reactions. Any of the substituents may be selected. Suitable substituents A from the group R1, R2, R3, R4 and R5 are selected, for example, from the group consisting of the functional groups or derivatised functional groups consisting of amino, C1-C4alkylamino, C1-C4dialkylamino, hydroxy, oxo, thio, -NO2, carboxy, carbamoyl, sulfo, sulfamoyl, ammonio, amidino, cyano, formylamino, formamido and halogen, or are saturated or unsaturated aliphatic, cycloaliphaflc or heterocycloaliphatic radicals, carbocyclic or heterocyclic aryl radicals, condensed carbocyclic, heterocyclic or carbocyclic-heterocyclic radicals, which may in turn be combined with any others of these radicals and which may be substituted by the cited functional groups or derivatised functional groups.
The cited substituents and radicals can additionally be interrupted by one or more than one bivalent radical selected from the group consisting of xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94C (xe2x95x90O)xe2x80x94Oxe2x80x94, xe2x80x94Oxe2x80x94C(xe2x95x90O)xe2x80x94, xe2x80x94(xe2x95x90O)xe2x80x94N (C1-C4alkyl)xe2x80x94, xe2x80x94N(C1-C4alkyl)xe2x80x94C(xe2x95x90O)xe2x80x94, xe2x80x94S(xe2x95x90O)xe2x80x94, xe2x80x94S(xe2x95x90O)2xe2x80x94, xe2x80x94S(xe2x95x90O)xe2x80x94Oxe2x80x94,xe2x80x94S(xe2x95x90O)2xe2x80x94Oxe2x80x94, xe2x80x94Oxe2x80x94S(xe2x95x90O)xe2x80x94, xe2x80x94Oxe2x80x94S(xe2x95x90O)2xe2x80x94, xe2x80x94S(xe2x95x90O)xe2x80x94N(C1-C4alkyl)xe2x80x94, xe2x80x94S(xe2x95x90O)2xe2x80x94N(C1-C4alkyl)xe2x80x94, xe2x80x94(C1-C4alkyl)Nxe2x80x94S(xe2x95x90O)xe2x80x94, xe2x80x94(C1-C4alkyl)Nxe2x80x94S(xe2x95x90O)2xe2x80x94, xe2x80x94P(xe2x95x90O)xe2x80x94, xe2x80x94P(xe2x95x90O)xe2x80x94Oxe2x80x94, xe2x80x94Oxe2x80x94P(xe2x95x90O)xe2x80x94 and xe2x80x94Oxe2x80x94P(xe2x95x90O)xe2x80x94Oxe2x80x94.
Two substituents from the group R1, R2, R3, R4 and R5 can also be bivalent, bridge-like C2-C6alkylene, C4-C8alkyldiylidene or C4-C8alkenyldiylidene groups, preferably butanediylidene, more preferably 2-butenediylidene, which are bound to the phenyl ring D or to the heteroaryl substituent A, e.g. pyridyl, or which are condensed to an aromatic bicycle, which can likewise be substituted by the cited functional groups or substituents.
Suitable substituents B from the group R6, R7, R8, R9 and R10 have the meanings cited for R1 to R5 and can also be substituted by further substituents. R1, R2, R3, R4 and R5 and R6, R7, R8, R9 and R10 are defined each independently of one another.
Suitable substituents A from the group R1, R2, R3, R4 and R5 are preferably functional groups from the group consisting of amino, C1-C4alkylamino, for example methylamino or ethylamino, C1-C4dialkylamino, for example dimethylamino or diethylamino, hydroxy, oxo, thio, xe2x80x94NO2, carboxy and halogen, or are substituents from the group C1-C20alkyl, C2xe2x80x94C 20alkenyl, C2-C20alkynyl, C3-C12cycloalkyl, C7-C12bicycloalkyl, C4-C12cycloalkenyl, C2-C11heterocycloalkyl, carbocyclic C6-C16aryl, C2-C15heteroaryl, carbocyclic C7-C16aralkyl and C2-C15heteroarylalkyl, which can in turn be substituted by the cited functional groups and which can be interrupted by bivalent radicals.
C1-C20Alkyl is, for example, methyl, ethyl, n- or isopropyl or n-, sec- or tert-butyl and also straight-chain or branched pentyl, hexyl, heptyl, octyl, isooctyl, nonyl, tert-nonyl, decyl, undecyl or dodecyl.
C2-C20Alkenyl is, for example, vinyl, allyl, 2-or 3-butenyl, isobutenyl or n-penta-2,4-dienyl.
C2-C20Alkynyl is, for example, 1- or 2-propynyl.
C3-C12Cycloalkyl is, for example, cyclopropyl, dimethylcyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.
C7-C12Bicycloalkyl is, for example, bornyl or norbornyl.
C4-C12Cycloalkenyl is, for example, cyclopentadienyi or cyclohexenyl.
C2-C11Heterocycloalkyl preferably contains 4 or 5 carbon atoms and one or two heteroatoms from the group O, S and N. Examples are the substituents derived from oxirane, azirine, 1,2-oxathiolane, pyrazoline, pyrrolidine, piperidine, piperazine, morpholine, tetrahydrofuran or tetrahydrothiophene.
Carbocyclic C6-C16aryl is, for example, mono-, bi- or tricyclic, typically phenyl, naphthyl, indenyl, azulenyl or anthryl.
C2-C15Heteroaryl is preferably monocyclic or is condensed with another heterocycle or with an aryl radical, e.g. phenyl, and preferably contains one or two, in the case of nitrogen up to four, heteroatoms selected from the group consisting of O, S and N. Suitable substituents are derived from furan, thiophene, pyrrole, pyridine, bipyridine, picolylimine, xcex3-pyrane, xcex3-thiopyrane, phenanthroline, pyrimidine, bipyrimidine, pyrazine, indole, coumarone, thionaph thene, carbazole, dibenzofuran, dibenzothiophene, pyrazole, omidazole, benzimidazole, oxazole, thiazole, dithiazole, isoxazole, isothiazole, quinoline, isoquinoline, acridine, chro mene, phonazine, phenoxazine, phenothiazine, triazine, thianthrene, purine or tetrazole.
Carbocyclic C7-C16aralkyl preferably contains 7 to 12 carbon atoms, for example benzyl, 1- or 2-phenethyl or cinnamyl.
C2-C15leteroarylalkyl preferably consists of the cited heterocycles which substitute e.g. C1-C4alkyl radicals, depending on the length of the carbon chain where possible terminally or else also in adjacent position (1-position) or in xcex1-position (2-position).
In an aromatic olefin of formula II, the index o preferably means 1 to 5. The phenyl ring F is preferably substituted by 1 to 5 substituents C from the group containing the substituents R1, R2, R3, R4 and R5which are as defined above under formula I for A and R1 to R5. In the olefinic side chains, R6, R7 and R8 are hydrogen or substituents which are also as defined above under formula I for A and R1 to R5.
In the phenyl derivative of formula III a or III b used in accordance with process variant a), X is a leaving group which is expelled during the coupling reaction, the so-called Suzuki cross-coupling. This reaction type is illustrated by the following reaction for the preparation of a photoinitiator. 
A suitable leaving group X is known e.g. for the coupling reactions of the Suzuki type and is, for example, halogen, e.g. chloro, bromo or iodo, or an organosulfonyl radical, e.g. mesyl, p-toluenesulfonyl or trifluoromethanesulfonate. It has been found that chlorine is suitable as leaving group when the catalysts (VII a) are used. Otherwise, coupling reactions of the Suzuki type proceed with satisfactory yield and TON only when higher halogens, e.g. bromo or iodo, are used as leaving group. The above process is the first palladium catalyst-mediated coupling of a deactivated (by electron-rich or electron-shifting groups), substituted aryl chloride by the Suzuki method.
In a special process variant, the substituents A (m=1) or B (n=1) in a phenyl derivative of formula III a or III b can also be an additional leaving group X having the cited meanings. The phenyl derivative (III a, III b) concerned contains in this case two leaving groups X. It is possible to couple such a derivative with two equivalents of arylboronic acid derivatives of formula IV a or IV b so that a phenyl ring E is combined with two phenyl rings D in the process product which can be thus obtained. In analogy, products are obtained wherein one phenyl ring D is combined with two phenyl rings E.
In another process variant, it is possible that the substituents A and B in phenyl derivatives of formula III a or III b also contain additional leaving groups X. The phenyl derivative (III a, III b) concerned contains in this case two or more leaving groups X. Such a derivative can be coupled with corresponding equivalent arylboronic acid derivatives of formula IV a or IV b so that the phenyl rings D or E in the process product which can be thus obtained are additionally coupled to the substituents A or B with further phenyl rings D or E. This process variant is illustrated by the following coupling reaction: 
wherein cat. (above the reactions arrow) signifies the catalyst (VII a).
In the arylboronic acid derivatives of formulae IV a and IV b used in accordance with process variant a), Y is also a leaving group defined as xe2x80x94B(OH)2 or mono- or diester derivatives ofxe2x80x94B(OH)2. Mono- or diester derivatives ofxe2x80x94B(OH)2 are, for example, xe2x80x94B(Oxe2x80x94C1-C4alk)2 or xe2x80x94BOHxe2x80x94C1-C4alk, where C1-C4alk is preferably methyl or ethyl, xe2x80x94B(Oxe2x80x94Ar)2 or xe2x80x94BOHxe2x80x94Ar, where Ar is preferably aryl.
In the phenyl derivative (V) used according to process variant b), the index o and the substituents C have the meanings cited for formula II. A suitable leaving group X is known, for example, for the Heck type coupling reactions and is typically halogen, e.g. bromo or iodo.
In an olefinic palladium complex compound of formula VII a, L is a neutral ligand having electron-donor properties. Suitable ligands are, for example, phosphine ligands of the tertiary phosphine type.
A suitable tertiary phosphine preferably contains 3 to 40, more preferably 3 to 18, carbon atoms and preferably conforms to formula:
PR1R2R3xe2x80x83xe2x80x83(VIII),
wherein R1, R2 and R3 are each independently of one another C1-C20alkyl, C4-C12cycloalkyl, C2-C11heterocycloalkyl, C6-C16aryl, C7-C16aralkyl or C2-C15heteroarylalkyl having the meanings cited above, which radicals may be substituted by substituents selected from the group consisting of C1-C6alkyl, C1-C6alkoxy, C1-C6haloalkyl, C6-C16aryl, xe2x80x94NO2, SO3, ammonium and halogen. R1 and R2 together can be tetra- or pentamethylene which is unsubstituted or substituted by C1-6alkyl, C1-C6haloalkyl, xe2x80x94NO2 or C1-C6alkoxy which are condensed with 1 or 2 bivalent 1,2-phenylene radicals, R3 having the meaning cited above.
Also preferred are sterically exacting radicals R1, R2 and R3, for example cyclic or branched, particularly preferably xcex1,xcex1-dibranched and, very particularly preferably xcex1-branched, alkyl groups.
Particularly preferred are those compounds (VII), wherein R1, R2 and R3 are methyl, ethyl, n- or i-propyl, n-, i-, s- or t-butyl, 1-, 2- or 3-pentyl, 1-, 2-, 3- or 4-hexyl, cyclopentyl, cyclohexyl, phenyl, naphthyl or benzyl, for example (i-C3H7)3P, (C5H9)3P and (C6H11)3P.
An anionic ligand is, for example, the hydride ion (Hxe2x88x92) or a ligand which is derived, for example, from inorganic or organic acids by the splitting off of protons, e.g. a halide (Fxe2x88x92, Clxe2x88x92, Brxe2x88x92 and Ixe2x88x92) or anions of oxygen acids or derivatives thereof, for example SnCl3xe2x88x92, SnCl5xe2x88x92, BF4xe2x88x92, B(aryl)4xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92 or AsF6xe2x88x92.
Anions of oxygen acids are, for example, sulfate, phosphate, perchlorate, perbromate, periodate, antimonate, arsenate, nitrate, carbonate, the anion of a C1-C8acarboxylic acid, for example formiate, acetate, propionate, butyrate, benzoate, phenylacetate, mono-, di- or trichloro- or fluoroacetate, sulfonates, for example mesylate, ethanesulfonate, propanesulfonate, n-butanesulfonate, trifluoromethanesulfonate (triflate); benzenesulfonate or p-toluenesulfonate which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy or halogen, in particular by fluoro, chloro or bromo, for example benzenesulfonate, tosylate, p-methoxy or p-ethoxybenzenesulfonate, pentafluorobenzenesulfonate or 2,4,6-triisopropylbenzenesulfonate.
Particularly preferred anionic ligands are Hxe2x88x92, Fxe2x88x92, Clxe2x88x92, Brxe2x88x92, BF4xe2x88x92, PF6xe2x88x92, SnCl3xe2x88x92, SbF6xe2x88x92, AsF6xe2x88x92, CF3SO331 , C6H5-SO3xe2x88x92, 4-methyl-C6H5-SO3xe2x88x92, 3,5-dimethyl-C6H5-SO3xe2x88x92, 2,4,6-trimethyl-C6H5-SO3xe2x88x92 and 4-CF3-C6H5-SO3xe2x88x92 and also cyclopentadienyl (Cpxe2x88x92). Clxe2x88x92, Brxe2x88x92, or Ixe2x88x92 are particularly preferred.
Suitable substituents D remain unchanged under the conditions of the coupling reactions. Any substituents may be chosen. Suitable substtuents D are selected from the group consisting of R1, R2, R3, R4 and R5. Index p is preferably 1 and 2. Suitable substituents are typically selected from the group consisting of hydroxy, halogen, e.g. chloro, carboxy and esterified carboxy, e.g. methoxy- or ethoxycarbonyl, or are saturated or unsaturated aliphatic, cycloaliphatic or heterocycloaliphatic radicals, carbocyclic or heterocyclic aryl radicals, condensed carbocylic, heterocyclic or carbocyclic-heterocyclic radicals or suitable combinations of these radicals, which may in turn be substituted by one or more than one substituent from the group consisting of hydroxy, halogen, oxo, esterified carboxy, e.g. ethoxy- or methoxycarbonyl, and acyl, e.g. acetyl.
Suitable olefinic palladium complex compounds (VII a) containing substituents at the allyl group are represented by the following structural formulae: 
wherein X and L have the cited meanings and are preferably tricyclohexylphosphine or triisopropylcyclophosphine and halogen, typically chloro, bromo or iodo.
The substituents of the allyl group can also be combined to polynuclear bridged complexes in the sense of the following structure: 
Preferred olefinic palladium complex compounds (VII a) are those containing no subsbtuents at the allyl group which is bound to palladium (index p is 0), L is the tricyclohexylphospine or triisopropylcyclophosphine group and X is halogen, typically chloro, bromo or iodo.
In an olefinic ionic palladium complex compound of formula VII b, D and p have the meanings cited above for compounds of formula VII a. The index p is preferably 0. The meanings of the anionic ligands of Z1 and Z2 correspond to the meaning of Z. Z1 and Z2 are preferably halogen, typically chloro, bromo or iodo. The non-coordinating cation K+ is voluminous and corresponds in size to the palladium complex anion which carries a negative charge because of the presence of the second anionic ligand Z2. A preferred non-coordinating cation K+ is, for example, the tetraphenylphosphonium cation.
The reaction conditions for the coupling reactions are described in the literature and correspond to the reaction conditions known for the so-called Suzuki coupling and Heck coupling reactions.
The process of this invention is preferably carried out such that the reactants can be reacted with each other in any order. Preferably, the phenyl derivatives with the leaving groups X, i.e. compounds of formula III a or III b, or compounds V, are placed first in a vessel and then the arylboronic acid derivatives of formula IV a or IV b or the olefin compound (VI) are added.
In the sense of a cross-coupling, the phenyl rings D and E can be combined to the combination D with E by using the starting materials III a and IV a, to the combination D with D by using the starting materials III a and IV b to the combination E with E by using the starting materials III b and IV a, and to the combination E with D by using the starting materials III b and IV b.
The term catalytic amounts preferably means amounts of about 0.0001-5.0 mol %, more preferably of 0.001-1.0 mol %, based on the amount of the substrate used.
The molar ratio of the reactants of the coupling reactions of the compounds of formula III a or III b to the arylboronic acid derivatives of formula IV a or IV b, or of the compounds (V) to the olefin compound (VI), is usually in the range from 1:1 to 1:10, the preferred ratio being in the range from 1:1 to 1:2. The reaction is carried out at temperatures up to the boiling temperature of the solvent, preferably at room temperature up to the boiling temperature of the solvent (reflux conditions). Suitable solvents are customary, preferably higher-boiling, solvents, for example non-polar aprotic solvents, e.g. xylene or toluene, or polar aprotic solvents, e.g. dimethylformamide. The obtainable reaction product (I) or (II) is worked up and isolated in a manner known per se by conventional purification processes, for example after removal of the solvent and subsequent separation processes, such as precision distillation, recrystallisation, preparative thin-layer chromatography, column chromatography, preparative gas chromatography and the like.
A particular embodiment of the process comprises
a) subjecting a phenyl derivative (III) for the preparation of the biphenyls (I) to a coupling reaction with an arylboronic acid derivative (IV); or
b) subjecting a phenyl derivative (V) for the preparation of the aromatic olefin (II) to a coupling reaction with an olefin (VI),
each in the presence of an olefinic palladium complex compound (VII a), wherein L is a neutral ligand having electron-donor properties, Z is halogen and p is 0, or in the presence of an olefinic ionic palladium complex compound (VII b), wherein Z1 and Z2 are halogen, K+ is the tetraphenylphosphonium cation and p is 0 and, after carrying out the process variants a) or b), isolating the biphenyls (I) or the condensed aromatic olefin (II).
In a particularly preferred process variant, each of the coupling reactions are carried out in the presence of an olefinic palladium complex compound (VII a), wherein L is triisopropylphosphine or tricyclohexylphosphine, Z is halogen, typically chloro, bromo or iodo, and p is 0.
This invention also relates to olefinic palladium complex compounds of formula 
wherein L is a neutral ligand having electron-donor properties, I is iodine and D is substituents, and p is an integer from 0 to 5 and defines the number of the substituents at the allyl group.
A particularly preferred subject matter of this invention are palladium complex compounds of formula 
wherein i-Pr is isopropyl, Hal is chloro or bromo and D is substituents, and p is an integer from 0 to 5 and defines the number of substituents at the allyl group, and also olefinic complex compounds of formula 
wherein Cy is cyclohexyl, Cl is chloro and D is substituents, and p is an integer from 0 to 5 and defines the number of substituents at the allyl group.
A particularly preferred subject matter of this invention are the compounds of formulae 
The preparation of such olefinic palladium complex compounds, which are a subject matter of this invention, and of the known palladium complex compounds is carried out in a manner known per se by reacting a known dimeric allyl-halo-palladium complex with a compound introducing the ligand L, for example with triisopropyl- or tricyclohexylphosphine: 
This reaction can be carried out in analogy to the method according to B.{dot over (A)}kermark et al., Organometallics 1987, 6, 620-628 or Y.Hayashi et al. J.Chem. Soc. Dalton Trans. 1989, 1519.
This invention also relates to the process for the preparation of the novel olefinic palladium complex compounds (VII a).
The preparation of the dimeric allyl-halopalladium complexes is known and is described, inter alia, in Y.Tatsuno et al., Inorg. Synth. 1979, 14, 220; Y.Inoue et al. Synthesis, 1984, 3, 244; B. M. Trost et al. J. Amer. Chem. Soc. 1980, 102, 3572.
Olefinic ionic palladium complex compounds of formula VII b are known. Their preparation is described in R. J. Goodfellow et al., J. Chem. Soc. (A), 1966, 784.
The use of olefinic palladium complex compounds of formula VII a and of the olefinic ionic palladium complex compounds of formula VII b for the catalysis of coupling reactions of aromatic compounds with each other and of aromatic compounds with olefins is, in principle, novel and inventive. Accordingly, the use according to this invention relates both to known and to novel compounds which are covered by formulae VII a and VII b.
In another of its aspects, this invention relates to the use of an olefinic palladium complex compound of formula 
wherein L is a neutral ligand having electron-donor properties, Z is an anionic ligand and D is substituents, and p is an integer from 0 to 5 and defines the number of substituents at the allyl group, and to the use of an olefinic ionic palladium complex compound of formula 
wherein Z1 and Z2 are anionic ligands, K+ is a complex-stabilising cation and D is substituents, and p is an integer from 0 to 5 and defines the number of substituents at the allyl group, for the catalytic preparation of biphenyls or olefinic aromatic compounds by coupling reactions.
A preferred subject matter of this invention is the use of olefinic palladium complex compounds of formula VII a and of the olefinic ionic palladium complex compounds of formula VII b for the catalysis of coupling reactions in the sense of the Suzuki coupling of aromatic compounds and of the Heck coupling of aromatic compounds with olefins.
The following Examples illustrate the invention: